New model helps predict paper degradation and deformation
Amir Parsa Sadr defended his PhD thesis at the Department of Built Environment on June 19.
Paper is everywhere in our daily lives, from books and historical documents to packaging and high-speed printing systems. However, paper is highly sensitive to environmental conditions such as humidity and temperature. These changes can cause paper to deform, wrinkle, or degrade over time, which is a major challenge for preserving cultural heritage and ensuring the reliability of modern paper-based technologies.
In his PhD research, investigated how paper responds to changing environmental conditions and developed new methods to predict its long-term behavior. His dissertation, Multi-Scale and Multi-Physics Modeling of Degradation and Stability in Historical Paper Materials, focused on understanding the mechanisms that affect the stability and durability of paper materials.
Linking microscopic changes to visible damage
When environmental conditions change, moisture moves through paper and causes the material to expand unevenly. This process creates internal stresses that can lead to visible deformations such as curling, buckling, and wrinkling. Over time, chemical degradation weakens the paper fibers, reducing the strength and stability of the material.
Parsa Sadr developed a novel modeling framework that linked paper behavior across different scales, from the microscopic fiber structure to the behavior of an entire sheet. The model captured the effects of moisture, temperature, and acidity on the mechanical properties of paper and enabled predictions of how paper degrades over time.
Predicting degradation and wrinkling
A key contribution of the research was the development of tools to predict when paper becomes vulnerable to damage. The models made it possible to estimate how long paper can remain stable under specific environmental conditions and when deterioration is likely to occur.
Parsa Sadr also introduced a method for predicting the onset of local wrinkles, known as cockling. The research showed that short-term fluctuations in humidity are often harmless, while prolonged exposure can result in permanent deformation. These insights were used to develop practical guidelines that relate environmental conditions to the risk of damage.
Benefits for industry and cultural heritage
The findings have applications in both industry and conservation. In printing and paper-handling systems, the models can help improve performance and reduce failures caused by environmental changes. For museums, libraries, and archives, the research provides a scientific basis for defining safe storage conditions and preventing damage to historically valuable documents.
By combining multiple physical processes and scales into a single modeling framework, Parsa Sadr's work contributed to a deeper understanding of how paper responds to its environment. The resulting tools can help predict and prevent degradation, supporting the preservation and reliability of paper-based materials for future generations.
Title of PhD thesis: Supervisors: Akke Suiker and Emanuela Bosco.